Metal treating fuknace and methob



METAL TREATING FURNACE AND METHOD Filed Feb. ll, 1936 5 Sheets-Sheet 2.

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5m. 24, 1939, H. A, DREFFEN 2,145,074

METAL TREATING FURNACE AND METHOD Filed Feb. ll, 1936 3 Sheets-Sheet 3Patented Jan. 24, 1939 UNITED STATES FATENT OFFICE 7 Claims.

This invention relates to annealing furnaces and has more particularreference to a furnace for heat treating metal sheets, strips, coils,plates, and similar members under desired atmospheric conditions in thefurnace and to a novel method of annealing.

An important object of the invention is the provision of a novel and animproved furnace of the movable bell type.

Another important object of the invention is the pro-vision of a movablework enclosing shield or shell within such a furnace, so constructed andarranged that desired atmospheric conditions may be established andmaintained therein.

A further important object of the invention is to provide a pressurestabilizing or compensating seal for preventing, or at least minimizing,the infiltration of air or other undesirable gases or mixtures thereofinto the work enclosing shell if or when, during the operation of thefurnace, a pressure differential occurs between the inside and theoutside of the shell.

An additional important object of the invention is to provide such aseal for minimizing interference between convection currents in the workenclosing shell by the occurrence of a pressure differential between theinside and the outside of the shell, whereby to promote the efficientheat distribution and circulation within the shell.

Another important object of the invention is to provide work supportingmeans constructed and arranged to promote a uniform distribution of heatby convection in the work enclosing shell, whereby work on thesupporting means in the shell will be heat treated on all sides.

Further important objects of the invention include the provision of adirect-fired annealing furnace of the movable bell type; a movable workenclosing shell within and spaced from the fur- 40 nace to provide acombustion chamber therebetween; a base for accommodating the furnaceand the work enclosing shell; a seal between the base and the furnace; apressure regulating seal between the base and the work enclosing shell;work supporting means on the base in the shell providing heat passagesunder the work for uniformly distributing the heat about the work;burner means arranged in the combustion chamber to direct the flamedownwardly, and at such a level that the discharge pressure of theburner means will project the ame to adjacent the base for supplyingmaximum heat at the bottom of the combustion chamber and permitting theheat then to circulate about the work enclosing shell; such burner meansin the combustion chamber (Cl. 26S-5) being adjustable for providing theproper amounts of heat in the furnace at the beginning, during, and atthe end of the heat treatment operation; and a novel method of annealingin a movable furnace with a work enclosing shell therein by establishingdesired atmospheric conditions in the annealing chamber, sealing thatchamber to maintain such conditions, and directly firing the furnace.

Other objects of the invention will be apparent from the followingdescription, and from the accompanying drawings, in which similarcharacters of reference refer to similar parts throughout the severalviews.

In the drawings,

Fig. 1 is a plan view, partially in section, of a furnace embodying thefeatures of the invention;

Fig. 2 is a side elevational vie'w partially in cross section, of thefurnace shown in Fig. 1;

Fig. 3 is an end elevation, partially in section, of the novel furnace;

Fig. 4 is a diagrammatic sectional view of the furnace shown in thepreceding figures, and illustrates the assembly of the novel furnace;

Fig. 5 is a fragmentary detail of a slightly different form of seal fromthat shown in Fig. 2;

Fig. 6 is an elevational view partially in section, of one of theburners employed in the novel furnace, and showing certain details ofconstruction and assembly;

Fig. 7 is an elevational View of the inlet end of the burner shown inFig. 6;

Fig. 8 is a cross section taken substantially along the lines 8 8 ofFig. 6;

Fig. 9 is a cross section taken substantially along the lines 9-9 ofFig. 6; and

Fig. 10 is a fragmentary cross section taken substantially along thelines Ill- Hl of Fig. 8.

Illustrative of the invention, the novel furnace of the invention asshown in Figs. l to 3, may be briefly and generally described ascomprising a base l5, work supporting means i6, on the base forsupporting, for example, metal sheets l1 to be treated, a work enclosingshell or shield I8 for providing a treating chamber i9 about the work,and a movable furnace 2| of the bell type, arrangeable on the base l5about, and in spaced relation with, the shell I8 for providing acombustion chamber 272 about the shell.

The base i5 is constructed to provide a foundation 23 of suitableconstruction, a foundation covering 24 of any suitable insulating orrefractory material. and a retaining structure preferably of metalsheets 25, channels 26, and corner or angle members 2l, arranged aboutthe sides of the base and extending to a level above that of theinsulating base covering 24. Such a base may, as .shown in Figs. l to 3,be rectangular in top plan View and is adapted to carry thereon, ifdesired, furnace aligning pins or studs 23 fixed in diagonally oppositecorners of the base i5 and extending upwardly therefrom for engaging inapertured brackets 29 correspondingly positioned on the movable furnace2l during the assembly of the furnace on the base.

The work supporting means it may be generally rectangular in plan, ofsmaller plane dimensions than the base, and is constructed and arrangedcentrally thereof. t comprises a mounting layer 3! of insulating orrefractory material carrying thereon a metal pan 32 with upstandingsides 33 spaced inwardly of the metal sheets 25 and providing or deningtherewith a trough or channel 3d circumscribing the sides 3S of the pan32 for carrying an appropriate sealing agent 35. In and centrally of thepan 32 a plurality of spaced upstanding members of insulating orrefractory material carry a work supporting metal plate El. The membersSii are arranged to extend Itransversely of the 32 beginning and endingat positions respectively spaced inwardly from the end sides 33 of thepan and are 0f such length that their opposite ends are spaced inwardlyfrom the longitudinal sides of the pan. Thus a trough or channel 35 isprovided between the sides of the pan and spaced members 36 for carryinga suitable sealing agent 3*.

The work enclosing shell I8 is of metal construction With side walls di,end walls LZ2, and a top or roof 43, and is provided with eyelet meanslil to facilitate positioning the shell on the base and removing ittherefrom. The dimensions and configuration of the shell iii are suchthat the side walls are receivable in the channel 35 between the sidesof the pan 32 and the members 36.

For cooperating with the sealing agent 39 to provide a seal about thelower edges of the shell i3 between the treating chamber i9 and thecombustion chamber 2 2, the lower marginal portions of the side and endwalls 4i and 42 are constructed to provide one (see Figs. l to fi) ormore (Fig. 5) sealing spaces or passages 45 receivable in 'the channel3B. Such a passage or such passages may be provided at the lowerperipheral margin of the shell i8 by a flange-like member conforming tothe configuration of the shell and connecting therewith above the loweredges of the side and end walls. Such iiange-like member is providedwith an outwardly extending portion 46 and, connecting therewith, adepending portion 47 spaced from the walls of the shell i8 to provideone passage iii or, if desired, a plurality of spaced depending portions4S (Fig. 5) connecting with the outwardly extending portions 6 andspaced from the walls of the shell i8 to provide a plurality of thepassages 4E.

The movable furnace 2i comprises two side walls fle, two end walls 5l,and a roof or crown constructed of a suitable refractory material in ametal casing that is reinforced by a suitable frame or superstructureEil. In the roof or crown are provided a plurality of flue openings 55,and suitable eyelet means is constructed on the superstructure or frame54 to facilitate positioning the furnace on the base and removing ittherefrom. The dimensions and configuration of the movable furnace 2lare such that the walls 49 and 5i thereof are adapted to seat in thetrough or channel 34 for cooperating with the sealing agent 35 toprovide a seal about the bottom of the movable furnace between theinside and the outside of the combustion chamber 22.

A plurality of individual burners 5l' are arranged in the combustionchamber 2 above the bottom thereof and project through the side walls i9of the furnace 2i. At their outer ends the burners 5l are provided withsuitable connections liil communicating with a fuel supply mann fold 5S'and with connections Si communicating With a supply pipe 62 forsupplying air for combustion to tie burners. Those burners El' arerespectively associated at their ends in the combustion chamber 22 withindividual hoods 63 of suitable refractory material and secured in anydesired manner over the burners along the walls 49 in the combustionchamber to provide a downwardly extending passage iid for each burner,communicating at its lower end with the com.- bustion chamber.

In determining the position of the burners 5': above the bottom of thecombustion chamber 22 in the direct-fired, movable furna the burnerdischarge pressure is considered and. the burners are arranged at such aheight that the pressure employed will carry the flame to adjacent thebottom of the combustion chamber for supplying the maximum heat where itis most needed. If the burners are too near the bottom for the pressureemployed, the sealing agent 3S may be disturbed with the result thatcombustion products or gases may pass from the combustion chamber intothe treating chamber and deleteriously affect the work. If, on the otherthe burners are too high, the heat at the bottom of the coinbust'ionchamber may be considerably less than the heat at the top thereof withthe result that all of the work is not uniformly heated. i have .foundthat the best results are obtained when the burners are arranged, withreference to the discharge pressure thereof, at such a distance abovethe bottom of the combustion chamber 22 that the burner flames will justbarely reach thc bottorn of the combustion chamber.

While the burners 5l may be of any suitable construction, the ends ofthe invention are best served by employing multi-nozzle, adjustableburners of the type illustrated in Figs. 6 to i0. Such burners have theadditional advantage of facilitating the bringing of the furnace up toproper heat conditions after which the heat sup- Y plied may be adjustedto a value for maintaining such conditions. Each such burner 5l,accordingly, comprises an outer an` supply fixture 65, an inner fuelsupply xture and an assembly head or fixture 61 provided with a closuremeinber 63 at its outer end. That assembly head 61 serv-es as a mountingfor the air supply fixture 65 and the fuel supply fixture G5. For thatpurpose the assembly head has adapter fixture Eil connectible incommunication with one of the connections Sill and extending through theclosure member $8 for connection at its other end to the fuel fixtureSii; and communicating connecting portions 'il and i2. The connectingportion 'ii of each assembly head is connectible to one of theconnections 6l. and the connecting portion 'l2 is connected to the airxture 65.

The air xture 55 is provided near its inner or discharge end with aplurality of discharge apertures or orifices i3 of the same or differentsizes and, respectively aligned therewith are a plurality of fueldischarge apertures or orifices 74 of the same or different sizes in thefuel fixture 66. By such a construction, fuel supplied to the fuel xture66 may be discharged through one or more of the orifices 14, mixed withair supplied to the air fixture B5, and the combustible mixturedischarged through one or more of the orifices 73. For adjusting thefuel and air supplied by the novel burner, a slidable valve member 'I5is arranged in the air fixture 65 between the inner wall thereof and theouter wall of the fuel fixture 65. That valve member 'I5 is constructedto provide a surface I6 for closing an orifice 'I3 in the air fixture 65and a surface 'I'I for closing an orifice 'I4 in the fuel fixture 85when the valve member is moved longitudinally of the burner in onedirection, and to open those orifices when the valve member is moved inthe opposite direction.

Valve operating means in the form of a reciproca-ble rod 'I8 is securedas at 'I9 to the valve member 'I5 and extends outwardly therefrom,longitudinally of and between the coaxial fixtures 65 and G6, throughthe closure member 88, outside of which the rod 'I8 is guidablysupported in a bracket 8| suitably secured tothe assembly head 61 and isprovided with means 82, for limiting the reciprocable movement of therod. Each hood 63 may be provided with a bayonet slot 83 for cooperationwith a lug 84 on each burner for holding the hood in position.

For establishing the desired atmospheric conditions in the treatingchamber IB, I provide means, diagrammatically illustrated at 85 in Figs.1 to 4, which provides communication between the inside and the outsideof the chamber. Means, diagrammatically illustrated at 85, providescommunication between the inside and outside of the sealing spaces orchambers 45 for establishing the proper atmospheric conditions thereinfor maintaining the atmospheric conditions in the treating chamber.

In operation, the sheets I'I or other work to be treat-ed is placed onthe work supporting plate 37 of the work supporting means I6, and anoverhead crane is employed to lower the work enclosing shell I8 and themovable furnace 2I to their respective positions on the base I with theshell I8 inwardly of and spaced from the furnace 2l, thus forming thetreating chamber I9 inside of the shell and the combustion chamber 22between the shell and the furnace. In thus assembling the novel furnace,the sealing chambers about the lower marginal portions of the shell I8are positioned in communication with the means 86 for establishing theproper atmospheric conditions in the sealing chambers, and the sealingagent 38, for example, sand, may be tamped in the channel 39 about theouter depending walls of the sealing chambers. The lower edges of thefurnace 2| seat in the channel 34, and the sealing agent 35 is employedto seal between those edges and the bottom of the channel.

After the furnace has been assembled on the base I5, the means 85 and 86may be employed for providing the desired atmosphere in the treatingchamber I9 and in the sealing chamber 4.5 thereabout, for example, asuitable gas such as coke producer gas, deoxidized natural gas, or anyatmosphere for protecting or desirably aecting the work, may be suppliedto or established in the treating and sealing chambers by the means 85and 86. When the desired atmospheric conditions have been reached in thetreating chamber, the means 85 may be adjusted in any well known mannerto: reduce or to terminate its action in supplying'gas to orestablishing other desirable atmospheric conditions in the treatingchamber, whereupon the means 86, cooperating with the sealing chamber 45and the sealing agent 39, effectively seals off the treating chamber formaintaining the atmospheric conditions established therein.

With such sealing means about the treating chamber, if a pressuredifferential between the outside and the inside of the treating chamberis caused by, for example, temperature variations, variations ofpressure in the combustion chamber 22 due toy combusti-on conditionstherein, or to changes in the air and/or fuel supply pressures, orwhatever the cause, that pressure differential will not produce theobjectionable pressure oscillations about the lower edges of the shellI8, or if such pressure oscillations are produced, they will not resultin a transfer of combustion gases or atmosphere from the combustionchamber into the treating chamber because the atmosphere in the sealingchamber 45, being under pressure, acts first to oppose the infiltrationof gas from the combustion chamber into the sealing chamber, andsecondly to provide an atmosphere that protects or otherwise desirablyaffects the work if any gas from the sealing chamber should be, bydisplacement from gas seeping therein from the combustion chamber,transferred into the treating chamber.

During the first step of the heat treatment, the burners 5'1 alongopposite sides of the movable furnace ZI may be operated with all of thedischarge orifices 'I3 and 'I4 open until the furnace is brought up tothe desired temperature, whereupon the reciprocable rods 'I8 may bepushed inwardly to the position shown in Fig. 6 to move the slidablevalve members 'I5 to a position for closing a sufficient number of thealigned orifices I3 and I4 for adjusting the heat supply to a valuesuicient to maintain the desired heat conditions in the furnace.

It will be seen that the flames from the burners 51 will be directeddownwardly toward the bottom of the combustion chamber for supplyingheat where it is most needed, and the heat thus supplied may circulatein the combustion chamber about the shell I8 for heating the worktherein. As the atmosphere in the treating chamber within the shell I8is thus heated by the directfired furnace 2 I, heat distribution may beeffect? ed by convection under the work between succeeding spacedmembers 36 andy on all sides of the work for effective and eicient heattreatment thereof.

Thus, by directly firing the furnace, heat transfer losses areminimized. 'Ihat desirable result is made possible by the novel andeffective seal between the combustion and treating chambers, whichinsures the maintenance of proper atmospheric conditions in the treatingchamber without, or at least with only a minimum of, contamination bygases having a deleterious effect upon the work seeping into thetreating chamber. The sealing means and the direct firing thus cooperatewith the n-ovel burner and the means for permitting a uniformcirculation of heat in the treating chamber for efiicientlyheat-treating the work therein.

While I have illustrated and described a preferred embodiment of myinvention, many modications may be made without departing from thespirit of the invention, and I do not wish to be limited to the precisedetails set forth but desire to avail myself of all changes within thescope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. A furnace comprising a base, a work enclosing shell mounted on saidbase and providing a treating chamber in the shell, a shell enclosingbell removably mounted on said base about and in spaced relation withsaid shell for providing a combustion chamber in said bell about saidshell, a burner in a side wall of said bell and having adjustable outletmeans in said com- 'bustion chamber and having inlet means outside ofsaid bell, and means extending outside of said bell for adjusting saidadjustable outlet means.

2. A furnace comprising a base, a movable work enclosing shell thereonproviding a treating chamber about the Work and having a sealing chamberadjacent the base and surrounding the shell, a movable shell enclosingbell on the base about and in spaced relation with the shell forproviding a combustion chamber in the bell about the shell, and aplurality of multi-nozzle burners in the combustion chamber.

3. A furnace comprising a base, a movable work enclosing shell thereonproviding a treating chamber about the work and having a sealing chamberadjacent the base and surrounding the shell, a removable shell enclosingbell on the base about and in spaced relation with the shell forproviding a combustion chamber in the bell about the shell, a pluralityof burners in said combustion chamber, adjustable means in saidcombustion chamber for adjusting each said burner, and means outside ofsaid combustion chamber for adjusting said adjustable means.

4. In a furnace of the movable bell type, a treating chamber, acombustion chamber around said treating chamber and separated therefrom,burner means having a plurality of burner outlets in said combustionchamber to direct flames, and burner outlet control means in saidcombustion chamber andy operable from outside thereof for controllingsaid burners.

5. In a furnace, a base, a movable outer bell, an inner bell spaced fromsaid outer bell to provide a combustion chamber therebetween, and burnermeans in said combustion chamber above said base and directed downwardlyfor providing a plane that extends barely to the bottom of saidcombustion chamber.

6. In a furnace of the movable bell type, a treating chamber, acombustion chamber separated therefrom and surrounding said treatingchamber, and downwardly directed burner means arranged in saidcombustion chamber so that with reference to the discharge pressure ofsaid burner means the flames therefrom will barely reach the bottom ofthe combustion chamber.

7. In a furnace of the movable bell type, a method of heat treatmentwhich comprises providing a treating chamber in and separated from acombustion chamber, forming a sealing chamber around the bottom of thetreating chamber and between it and the combustion chamber, establishinga work affecting atmosphere in the sealing chamber, directly firing thecombustion chamber, and extending the flame downwardly barely to thebottom of the combustion chamber.

HENRY A. DREFFEIN.

